diff --git a/ext/flash/lib.rs b/ext/flash/lib.rs
index 92490e0b8f..273aff02d3 100644
--- a/ext/flash/lib.rs
+++ b/ext/flash/lib.rs
@@ -373,11 +373,9 @@ unsafe fn op_flash_respond_fast(
   let ctx = &mut *(ptr as *mut ServerContext);
 
   let response = &*response;
-  if let Some(response) = response.get_storage_if_aligned() {
-    flash_respond(ctx, token, shutdown, response)
-  } else {
-    todo!();
-  }
+  // Uint8Array is always byte-aligned.
+  let response = response.get_storage_if_aligned().unwrap_unchecked();
+  flash_respond(ctx, token, shutdown, response)
 }
 
 macro_rules! get_request {
diff --git a/ops/optimizer.rs b/ops/optimizer.rs
index 82593d2473..7c19a7cfda 100644
--- a/ops/optimizer.rs
+++ b/ops/optimizer.rs
@@ -126,6 +126,10 @@ impl Transform {
           parse_quote! { *const #core::v8::fast_api::FastApiTypedArray<u32> };
 
         q!(Vars { var: &ident }, {
+          // V8 guarantees that ArrayBuffers are always 4-byte aligned
+          // (seems to be always 8-byte aligned on 64-bit machines)
+          // but Deno FFI makes it possible to create ArrayBuffers at any
+          // alignment. Thus this check is needed.
           let var = match unsafe { &*var }.get_storage_if_aligned() {
             Some(v) => v,
             None => {
@@ -141,17 +145,14 @@ impl Transform {
           parse_quote! { *const #core::v8::fast_api::FastApiTypedArray<u8> };
 
         q!(Vars { var: &ident }, {
-          let var = match unsafe { &*var }.get_storage_if_aligned() {
-            Some(v) => v,
-            None => {
-              unsafe { &mut *fast_api_callback_options }.fallback = true;
-              return Default::default();
-            }
-          };
+          // SAFETY: U8 slice is always byte-aligned.
+          let var =
+            unsafe { (&*var).get_storage_if_aligned().unwrap_unchecked() };
         })
       }
       TransformKind::WasmMemory => {
         // Note: `ty` is correctly set to __opts by the fast call tier.
+        // U8 slice is always byte-aligned.
         q!(Vars { var: &ident, core }, {
           let var = unsafe {
             &*(__opts.wasm_memory
@@ -166,13 +167,10 @@ impl Transform {
           parse_quote! { *const #core::v8::fast_api::FastApiTypedArray<u8> };
 
         q!(Vars { var: &ident }, {
-          let var = match unsafe { &*var }.get_storage_if_aligned() {
-            Some(v) => v.as_ptr(),
-            None => {
-              unsafe { &mut *fast_api_callback_options }.fallback = true;
-              return Default::default();
-            }
-          };
+          // SAFETY: U8 slice is always byte-aligned.
+          let var =
+            unsafe { (&*var).get_storage_if_aligned().unwrap_unchecked() }
+              .as_ptr();
         })
       }
     }
@@ -473,7 +471,6 @@ impl Optimizer {
                         match segment {
                           // Is `T` a u8?
                           PathSegment { ident, .. } if ident == "u8" => {
-                            self.needs_fast_callback_option = true;
                             assert!(self
                               .transforms
                               .insert(index, Transform::wasm_memory(index))
@@ -608,7 +605,6 @@ impl Optimizer {
               match segment {
                 // Is `T` a u8?
                 PathSegment { ident, .. } if ident == "u8" => {
-                  self.needs_fast_callback_option = true;
                   self.fast_parameters.push(FastValue::Uint8Array);
                   assert!(self
                     .transforms
@@ -645,7 +641,6 @@ impl Optimizer {
             match segment {
               // Is `T` a u8?
               PathSegment { ident, .. } if ident == "u8" => {
-                self.needs_fast_callback_option = true;
                 self.fast_parameters.push(FastValue::Uint8Array);
                 assert!(self
                   .transforms
diff --git a/ops/optimizer_tests/op_state_with_transforms.expected b/ops/optimizer_tests/op_state_with_transforms.expected
index d6757801ee..f5f236b7d9 100644
--- a/ops/optimizer_tests/op_state_with_transforms.expected
+++ b/ops/optimizer_tests/op_state_with_transforms.expected
@@ -3,7 +3,7 @@ returns_result: false
 has_ref_opstate: true
 has_rc_opstate: false
 has_fast_callback_option: false
-needs_fast_callback_option: true
+needs_fast_callback_option: false
 fast_result: Some(Void)
 fast_parameters: [V8Value, Uint8Array]
 transforms: {1: Transform { kind: SliceU8(true), index: 1 }}
diff --git a/ops/optimizer_tests/op_state_with_transforms.out b/ops/optimizer_tests/op_state_with_transforms.out
index 541a4fd36f..b2ded3c5a4 100644
--- a/ops/optimizer_tests/op_state_with_transforms.out
+++ b/ops/optimizer_tests/op_state_with_transforms.out
@@ -142,13 +142,7 @@ where
             as *const _ops::OpCtx)
     };
     let state = &mut ::std::cell::RefCell::borrow_mut(&__ctx.state);
-    let buf = match unsafe { &*buf }.get_storage_if_aligned() {
-        Some(v) => v,
-        None => {
-            unsafe { &mut *fast_api_callback_options }.fallback = true;
-            return Default::default();
-        }
-    };
+    let buf = unsafe { (&*buf).get_storage_if_aligned().unwrap_unchecked() };
     let result = op_now::call::<TP>(state, buf);
     result
 }
diff --git a/ops/optimizer_tests/raw_ptr.out b/ops/optimizer_tests/raw_ptr.out
index f9f467ad9b..cf678ddb9d 100644
--- a/ops/optimizer_tests/raw_ptr.out
+++ b/ops/optimizer_tests/raw_ptr.out
@@ -169,13 +169,7 @@ where
             as *const _ops::OpCtx)
     };
     let state = &mut ::std::cell::RefCell::borrow_mut(&__ctx.state);
-    let buf = match unsafe { &*buf }.get_storage_if_aligned() {
-        Some(v) => v.as_ptr(),
-        None => {
-            unsafe { &mut *fast_api_callback_options }.fallback = true;
-            return Default::default();
-        }
-    };
+    let buf = unsafe { (&*buf).get_storage_if_aligned().unwrap_unchecked() }.as_ptr();
     let out = match unsafe { &*out }.get_storage_if_aligned() {
         Some(v) => v,
         None => {
diff --git a/ops/optimizer_tests/uint8array.expected b/ops/optimizer_tests/uint8array.expected
index 0e5667a637..49554a2e83 100644
--- a/ops/optimizer_tests/uint8array.expected
+++ b/ops/optimizer_tests/uint8array.expected
@@ -3,7 +3,7 @@ returns_result: false
 has_ref_opstate: false
 has_rc_opstate: false
 has_fast_callback_option: false
-needs_fast_callback_option: true
+needs_fast_callback_option: false
 fast_result: Some(Bool)
 fast_parameters: [V8Value, Uint8Array, Uint8Array]
 transforms: {0: Transform { kind: SliceU8(false), index: 0 }, 1: Transform { kind: SliceU8(true), index: 1 }}
diff --git a/ops/optimizer_tests/uint8array.out b/ops/optimizer_tests/uint8array.out
index 90d420fa0d..bd7fa4d87e 100644
--- a/ops/optimizer_tests/uint8array.out
+++ b/ops/optimizer_tests/uint8array.out
@@ -158,7 +158,7 @@ impl<'scope> deno_core::v8::fast_api::FastFunction for op_import_spki_x25519_fas
     fn args(&self) -> &'static [deno_core::v8::fast_api::Type] {
         use deno_core::v8::fast_api::Type::*;
         use deno_core::v8::fast_api::CType;
-        &[V8Value, TypedArray(CType::Uint8), TypedArray(CType::Uint8), CallbackOptions]
+        &[V8Value, TypedArray(CType::Uint8), TypedArray(CType::Uint8)]
     }
     fn return_type(&self) -> deno_core::v8::fast_api::CType {
         deno_core::v8::fast_api::CType::Bool
@@ -168,24 +168,11 @@ fn op_import_spki_x25519_fast_fn<'scope>(
     _: deno_core::v8::Local<deno_core::v8::Object>,
     key_data: *const deno_core::v8::fast_api::FastApiTypedArray<u8>,
     out: *const deno_core::v8::fast_api::FastApiTypedArray<u8>,
-    fast_api_callback_options: *mut deno_core::v8::fast_api::FastApiCallbackOptions,
 ) -> bool {
     use deno_core::v8;
     use deno_core::_ops;
-    let key_data = match unsafe { &*key_data }.get_storage_if_aligned() {
-        Some(v) => v,
-        None => {
-            unsafe { &mut *fast_api_callback_options }.fallback = true;
-            return Default::default();
-        }
-    };
-    let out = match unsafe { &*out }.get_storage_if_aligned() {
-        Some(v) => v,
-        None => {
-            unsafe { &mut *fast_api_callback_options }.fallback = true;
-            return Default::default();
-        }
-    };
+    let key_data = unsafe { (&*key_data).get_storage_if_aligned().unwrap_unchecked() };
+    let out = unsafe { (&*out).get_storage_if_aligned().unwrap_unchecked() };
     let result = op_import_spki_x25519::call(key_data, out);
     result
 }
diff --git a/ops/optimizer_tests/wasm_op.expected b/ops/optimizer_tests/wasm_op.expected
index 98cfb4e7db..8d3719cf79 100644
--- a/ops/optimizer_tests/wasm_op.expected
+++ b/ops/optimizer_tests/wasm_op.expected
@@ -3,7 +3,7 @@ returns_result: false
 has_ref_opstate: false
 has_rc_opstate: false
 has_fast_callback_option: false
-needs_fast_callback_option: true
+needs_fast_callback_option: false
 fast_result: Some(Void)
 fast_parameters: [V8Value]
 transforms: {0: Transform { kind: WasmMemory, index: 0 }}